A significant hindrance of small molecule therapeutic development is translation from the laboratory to the clinic. A recent conference sponsored by the NIH Office of the Director on Rare Diseases recognized the challenge that many rare cancers do not receive adequate support from the NCI, thus additional funding mechanisms are necessary. Rare cancers not only require novel therapy, but many of their unique attributes can inform the therapy of more common diseases. We have generated data over the past eight years supporting direct targeting of an ideal cancer target in the very rare Ewing's Sarcoma. This ideal cancer target originates from a tumor-specific chromosomal translocation only present in the tumor and absent from normal cells. The chromosomal translocation causes the synthesis of a novel fusion protein, EWS-FLI1. This ideal target is a transcription factor and lacks enzymatic activity, thus direct targeting has generally been considered impossible. Our approach recognizes that cancer cell transcription is a highly-balanced process requiring multiprotein complexes for mRNA synthesis and regulation. Our hypothesis was that EWS-FLI1 presents a novel opportunity for targeted therapeutics by means of disrupting its protein-protein interactions. Earlier work identified RNA helicase A (RHA) as a critical partner for EWS-FLI1 and a recent publication revealed peptide and small molecule (YK-4-279) disruption of EWS-FLI1 from RHA caused Ewing's Sarcoma cell apoptosis. This RC4 mechanism provides an opportunity to directly advance these basic science discoveries into new and better treatments. In preparation for this application, we generated preliminary data that demonstrates oral absorption and minimal toxicity from YK-4-279 in three independent toxicology studies. We have also performed scale-up synthesis experiments as a precursor to good manufacturing practice (GMP) synthesis. The overall ambition of this proposal is to optimize delivery methods and obtain toxicologic data for submission of an investigational new drug (IND) application leading to a first-in-class, first-in-human clinical trial. The experiments presented in this proposal will potentially stimulate the opening of a novel area of pharmacologic development, that of small molecule protein-protein interaction inhibitors (SMPPII) for transcription. The talents of our multidisciplinary team enabled us to discover a successful small molecule, while the expanded team includes toxicologists, pharmacologists, and clinical trial developers. Following RC4 funding, this work would be sustainable by additional project grants from the NIH, philanthropy, and industry for small molecule development. This proposal includes a clinical trial that would sustain future phase 2 clinical trials to determine efficacy of YK-4-279 as a novel anti-cancer drug in specific diseases. Future growth will also arise from the targeting of additional cancers and other diseases that rely on aberrant transcription to improve human health. PUBLIC HEALTH RELEVANCE: The overall ambition of this proposal is to optimize delivery methods and obtain toxicologic data for submission of an investigational new drug (IND) application leading to a first-in-class, first-in-human clinical trial. The experiments presented in this proposal will potentially stimulate the opening of a novel area of pharmacologic development, that of small molecule protein-protein interaction inhibitors (SMPPII) for transcription. The talents of our multidisciplinary team enabled us to discover a successful small molecule, while the expanded team includes toxicologists, pharmacologists, and clinical trial developers. This proposal includes a clinical trial that would sustain future phase 2 clinical trials to determine efficacy of YK-4-279 as a novel anti-cancer drug in specific diseases. Future growth will also arise from the targeting of additional cancers and other diseases that rely on aberrant transcription to improve human health.